Improved Code Autocompletion

[code-xD]

Fixes #33425 improved code suggestions. Although work needs to be done on the GUI side to make sure the right letters of suggestions are highlighted.

[YeldhamDev]

You accidentally carried over the other commit.

[code-xD]

@aaronfranke @YeldhamDev I made the required changes you can now re-review the code.

[bojidar-bg]

Doesn't this still break in cases like this?

class X:
    const xabcxy = 0
    const xaxbxcy = 1
func _ready():
    print(X.abc<tab>) # Should display both, since X.abcy<tab> displays both

[aaronfranke]

@bojidar-bg Why would you want that? I don't see the use case for matching non-contiguous characters. By that logic, my previous sentence would match with "donuts" and "contact".

Btw, the old code doesn't do that either, so this PR is only an improvement from what I see.

[bojidar-bg]

What I meant to say is that while it is definitely an improvement, it is still possible to reproduce a form of #33425 after it.

[akien-mga]

Superseded by #34288, but thanks for the contribution nevertheless!